linux-kernel - Re: [PATCH v3] Introduce support for Systems Management Driver over WMI for Dell Systems

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Date:   Mon, 21 Sep 2020 15:08:30 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     Divya Bharathi <divya27392@...il.com>,
        Darren Hart <dvhart@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        Divya Bharathi <divya_bharathi@...l.com>,
        mark gross <mgross@...ux.intel.com>,
        Mario Limonciello <mario.limonciello@...l.com>,
        Prasanth KSR <prasanth.ksr@...l.com>
Subject: Re: [PATCH v3] Introduce support for Systems Management Driver over
 WMI for Dell Systems

On Mon, Sep 21, 2020 at 2:38 PM Hans de Goede <hdegoede@...hat.com> wrote:
> On 9/17/20 8:55 AM, Divya Bharathi wrote:

...

> Now I see that you try to correctly deal with strncpy-s nastiness
> everywhere, but please just don't use it all.
> Not using strncpy at all is much better.
>
> A lot of the strncpy usage is hidden in:
>
> strncpy_attr(char *dest, char *src)
> {
>          size_t len = strlen(src) + 1;
>
>          if (len > 1 && len < MAX_BUFF)
>                  strncpy(dest, src, len);
> }
>
> Why is there no warning printed when the source string
> is too long ? Now we just quietly throw away the
> data, which seems undesirable.
>
> Also wouldn't truncating the data to fit in MAX_BUFF be better?
> (honest question, I do not know which option is better)

And don't forget new compiler warning if it can prove that string will
be NUL-terminated.

-- 
With Best Regards,
Andy Shevchenko